In an existing wireless communication system in which the multi-user superposition transmission is adopted, a base station superposes data streams of different users with different transmission power being allocated based on channels of the users, a user equipment eliminates interference from other user equipment using for example a successive interference cancellation mechanism, and extracts a target data stream from the received superposed data stream. If extraction of the target data stream is failed, the user equipment may inform the base station that the target data stream is not extracted, and the base station may simply retransmit the data stream. However, if the retransmission is also superposition transmission, interference from other user equipment still exists in the retransmitted data stream. In this case, if the user equipment simply superposes the re-received data stream with the previously-received data stream to enhance the data stream, although power of the received signal is enhanced, power of the interfering signal may be also enhanced, resulting in a possibility of extracting the target data stream by retransmission is reduced.